My guess is that the fundamental driving force is this. There are great masses of people in a country like India living in abject poverty. If you're smart and lucky enough to have opportunity, what you have in India, that you don't have in a country like the United States, is day-to-day contact with the wretchedly poor. This staring you in the face puts your choices into stark relief.

In the U.S., for example, a bright young lady with opportunities can rest assured that, no matter what she chooses to study, life has a good chance of turning out alright for her. Her family, friends, teachers, and so forth generally agree. However in India, for example, it's far more likely that a bright young lady with opportunities will be thoroughly encouraged -- some might even say pushed -- to pursue only the most remunerative and prestigious occupations. In plain language: "Do you want to end up in the gutter?"

I wonder if these are the social structures that make the most difference.